loss_ratios parameter for event based risk calculation

[Hyeuk Ryu]

Hi,

Can you explain what the parameter of 'loss_ratios" is for event-based risk calculation?

Thanks.

Regards,

Hyeuk

[anirudh.rao]

Hi Hyeuk,

The loss_ratios parameter was recently introduced for the event based risk calculator, along with avg_losses and asset_loss_table. These new parameters are documented in the user manual for the upcoming release of OpenQuake v1.8. Below are brief descriptions of these parameters:

• loss_curve_resolution: this parameter specifies the number of points on the aggregate loss curve. The loss levels on the aggregate loss curve are obtained by dividing the interval between the minimum and maximum portfolio losses in the portfolio loss table into ‘n’ equispaced intervals, where ‘n’ is the value specified for the loss_curve_resolution. If this parameter is not set, the OpenQuake-engine uses a default value of 20 for the loss_curve_resolution.
  
  
• loss_ratios: this parameter specifies the set of loss ratios at which the individual asset loss curves will be computed for each loss category. If loss_ratios is not set in the configuration file, the individual asset loss curves will not be computed; and only the aggregate loss curve for the portfolio of assets will be computed. The example below specifies the loss ratios for structural and nonstructural loss curves; the exceedance probabilities in the individual asset loss curves will be computed at these loss ratios.
  loss_ratios = {"structural": [0.00010, 0.00016, 0.00025, 0.00040, 0.00065, 0.0010, 0.0016, 0.0025, 0.0040, 0.0065, 0.010, 0.016, 0.025, 0.040, 0.065, 0.10, 0.16, 0.25, 0.40, 0.65, 1.0], "nonstructural": [0.00010, 0.00016, 0.00025, 0.00040, 0.00065, 0.0010, 0.0016, 0.0025, 0.0040, 0.0065, 0.010, 0.016, 0.025, 0.040, 0.065, 0.10, 0.16, 0.25, 0.40, 0.65, 1.0]}
  
  
• avg_losses: this boolean parameter specifies whether the average asset losses over the time period “risk_investigation_time” should be computed. The default value of this parameter is false. In the specific case where risk_investigation_time = 1, setting avg_losses = true will compute the average annual loss (AAL) or expected annual loss (EAL).
  
  
• asset_loss_table: this boolean parameter specifies whether the individual asset event loss tables should be saved to the datastore. The default value of this parameter is false. Currently, if this parameter is set to true, the individual asset event loss tables will be saved in the HDF5 datastore, but these tables cannot be exported to CSV.
  

Regards,

Anirudh